A193 B7 Heavy Hex Bolts
The workhorse alloy-steel bolting grade for flanges, valves and pressure equipment — 125 ksi tensile, quenched and tempered 4140.
Larger heads for higher bearing area in heavy construction and flange service. Heavy pattern heads to ASME B18.2.1, commonly in A193 B7 and A325/A490 structural grades.
ASTM A193 Grade B7 is a quenched-and-tempered chromium-molybdenum alloy steel and the most specified bolting material in the process industries. It combines high strength with good toughness across the range of temperatures that flanged piping, valves, pumps and pressure vessels normally see, which is why it is the default stud-bolt grade under ASME B16.5 and B31.3.
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What A193 B7 must meet.
| Nominal diameter (in.) | Tensile strength, min (ksi) | Yield strength 0.2% offset, min (ksi) | Elongation in 4D, min (%) | Reduction of area, min (%) | Hardness, max |
|---|---|---|---|---|---|
| 2½ and under | 125 | 105 | 16 | 50 | 321 HBW / 35 HRC |
| Over 2½ to 4 | 115 | 95 | 16 | 50 | 321 HBW / 35 HRC |
| Over 4 to 7 | 100 | 75 | 18 | 50 | 321 HBW / 35 HRC |
Values per ASTM A193/A193M-24, Tables 1 and 2 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team.
Quenched in a liquid medium and tempered at 1100 °F (593 °C) minimum (A193 clause 6.1.5); furnace, induction or electrical-resistance heating is permitted. Threads are formed after heat treatment where practical. B7 carries no post-machining temper requirement; that applies to B7M (clause 6.1.6).
Full A193 B7 data sheet: chemistry, physical properties and standards →
Made to standard or to your drawing.
- Flange stud bolts for piping and pressure vessels
- Valve bonnet and body bolting
- Pump and compressor casings
- Heat exchanger channel covers
- Wellhead and Christmas-tree bolting (non-sour)
- Refinery and petrochemical structures